Tanzbar Player Concertina, Circa 1920
This amazing contraption looks like a regular small button concertina but the buttons are all fake. It is played by working the bellows in the usual fashion and working a small spring-loaded lever that advances a player piano-type roll which opens and closes the reed valves. They came in two versions, a 28 note accordion and a 16 note concertina (this one). This is a real tribute to German engineering, and is actually a well-made instrument.